How to scroll the parent of TextArea with cursor

[lyovushka]

TextArea scrolls itself when cursor (more accurately selection) changes. However when the scrollbar is on the parent, the cursor can wonder off while typing. Here is an example.

from textual.app import App
from textual.widgets import TextArea
from textual.widget import Widget


class TestWidget(Widget):
    DEFAULT_CSS = """
    TestWidget {
        height: auto;
        TextArea {
            height: auto;
        }
    }
    """

    def compose(self):
        yield TextArea()


class TestApp(App):
    def compose(self):
        yield TestWidget()


TestApp().run()

Keep pressing "enter" on the TextArea. A scrollbar appears on the Screen. But it doesn't scroll with the cursor. How to go about accomplishing that?

[willmcgugan]

If your custom widget is only going to contain a TextArea, then you would be better off simply extending TextArea rather than Widget.

[lyovushka]

In the actual thing, it does have other widgets.

[willmcgugan]

This is entirely expected behavior.

When you make your TextArea auto-expand, it can grow larger than its container (in this case the screen) which causes the container to scroll. The screen won't follow the TextArea cursor, but then there is no need to. TextAreas have their own scrollbar. If you limit the text area to the maximum dimensions of the screen, it will scroll with the cursor.

[lyovushka]

Do you mean something like "max-height: 1fr;" or similar? What if there are visible widgets above TextArea? Somehow they need to be scrolled out.

[willmcgugan]

I don't know what kind of UI you want to create. But you will need to decide how tall your text area should be. If it is inside a scrolling container and taller than the container it will be hard to use. You can set the maximum height of the text area. i.e. max-height: 100%; so that it never gets taller than its parent.

[lyovushka]

What I have in mind is a jupyter notebook - lots of text areas and other widgets all in a single vertical scroll. For now, I will listen to TextArea.SelectionChanged and adjust the scrolling on the parent. Not great, but gets the job done.